I thought I'd better sneak this post in while I have time. A reader from one of the facebook hobby groups I'm in identified the Pyro Twin 40mm Gun Motor Carriage as an M19 Multiple Gun Carriage. The M19 was built by GMC. Developed as an anti-aircraft gun it went into service in 1944 as an assault gun as by then the Allies had gained air superiority. It saw service in the Korean War as well.